Gas liquid separator for use in a refrigeration system

ABSTRACT

A gas liquid separator for use in a refrigeration circuit having a rotary compressor in which oil is mixed with refrigerant as the latter is circulated through the refrigeration cycle, said separator being situated between the compressor and the condenser portion of the cycle and including a swirl chamber for receiving the compressed refrigeration gas and oil mixture whereby the oil is centrifuged from the gas, collected and returned through an oil port to the inlet side of the compressor for recycling.

United States Patent [1 1 Lawser Dec. 18, 1973 GAS LIQUID SEPARATOR FOR USE IN A REFRIGERATION SYSTEM [75] lnventor: John J. Lawser, Dearborn Heights,

Mich.

[73] Assignee: Ford Motor Company, Dearborn,

Mich.

[22] Filed: Mar. 2, 1971 [21] Appl. No.: 120,147

[52] US. Cl 55/333, 55/337, 55/379, 55/421, 55/426, 55/459, 55/466, 55/473,

[51] Int. Cl Bld 50/00 [58] Field of Search 55/337, 257, 259, 55/486, 487, 488, 489, 525, 526, 379, 423,

[56] References Cited UNITED STATES PATENTS 1,915,987 6/1933 Fisher et a1. 55/337 X 2,010,456 8/1935 Jones 55/D1G. 17

Walton 55/487 X Ammons 55/337 2,846,138 8/1958 Racklyeft 55/DlG. 2,862,622 12/1958 Kircher, Jr. et a1... 210/411 3,099,546 7/1963 Smallpeice 55/379 X 3,269,097 8/1966 German 55/337 3,364,658 l/1968 Walker 55/DIG 17 2,473,602 6/1949 Lavigne 55/D1G. 3,271,934 9/1966 Shields /269 FOREIGN PATENTS OR APPLICATIONS 4,332 1905 Great Britain 55/337 Primary Examiner-Dennis E. Talbert, Jr. Attorney-John R. Faulkner and Donald J. Harrington 5 7 ABSTRACT A gas liquid separator for use in a refrigeration circuit having a rotary compressor in which oil is mixed with refrigerant as the latter is circulated through the refrigeration cycle, said separator being situated between the compressor and the condenser portion of the cycle and including a swirl chamber for receiving the compressed refrigeration gas and oil mixture whereby the oil is centrifuged from the gas, collected and returned through an oil port to the inlet side of the compressor for recycling.

1 Claim, 4 Drawing Figures PATENIEUUEE 1 8 m3 SHEUIBFZ RAM/M m/m ym JMa Z 4 GAS LIQUID SlEPARATOR FOR USE IN A REFRIGERATION SYSTEM GENERAL DESCRIPTION OF THE INVENTION The improvements of my invention may be used in an air conditioning system for an automotive vehicle which uses a refrigerant such as Freon. It is adapted especially to be used in an air conditioning system having a rotary compressor rather than a reciprocating piston compressor. Such rotary compressors may comprise rotary gear elements, preferably having helical threads, in which sealing between the high pressure side of the compressor and the low pressure side of the compressor is accomplished by the sealing action of the meshing gear teeth. Fluid is displaced as the pressure cavity defined in part by the gear teeth decreases in size upon rotation of the meshing gear elements.

It is necessary in arrangements of this type to provide a mixture of oil with the refrigerant in order to effect proper sealing between the high pressure side of the compressor and its low pressure side. Oil is required also to lubricate the compressor gear elements and to cool the compressor during operation of the regrigeration cycle.

In a preferred embodiment employing a rotary compressor in a circuit of this type, two parts of refrigerants are used for each part of oil. The oil and the compressed refrigerant gas at the discharge side of the compressor is in the form of an admixture. Since the oil is dispersed or atomized by the gas, the oil must be removed before the refrigerant can be used. For this reason, the admixture is passed through a separator, which separates the oil from the refrigerant and passes the refrigerant to a condensor which allows the pressurized gas to change to the liquid state.

The condensor in automobiles is the air-to-liquid radiator situated in the moving air stream caused by motion of the vehicle. The liquified refrigerant then is passed to an evaporator as the state changes from liquid to gas. An air blower circulates air over the evaporator to the vehicle passenger compartment so that a heat transfer takes place from the air to the evaporator.

The output side of the evaporator is connected through a low pressure gas line to the inlet side of the compressor as the cycle is repeated. The oil separated from the refrigerant at the separator is passed through a filter and through a valve cooler and hence to the inlet side of the compressor where it again is allowed to mix with the low pressure gas refrigerant supplied by the evaporator.

The improved separator of my invention includes two main chambers one of which is a swirl chamber which receives the admixture of oil and refrigerant, which preferably is Freon gas. Located directly under the swirl chamber is a collector chamber which receives oil centrifuged in the swirl chamber. A coalescer screen is situated in the central region of the swirl chamber where it may collect Freon gas separated by the centrifuging action of the swirl chamber. A baffle is concentrically disposed above the coalescer to prevent short circuiting or secondary flow of fluid directly from the inlet side of the separator to the coalescer. The axial dimensions of the baffle and the coalescer are chosen so that they will not at any time be lower than the level of the liquid in the collector chamber.

When the cycle is inoperative, Freon in liquid form and oil in liquid form collect in the collector chamber.

Freon has a higher specific gravity than oil. Therefore the oil rises to a level near one end of the coalescer and baffle. The baffle and the coalescer may be designed so that its capacity is sufficient to accommodate the swirling action while at the same time making it possible to prevent direct immersion of the baffle and coalescer in the uppermost fluid level in the collector chamber.

BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWING FIG. 1 shows in schematic form a refrigeration cycle for an automotive vehicle air conditioning system employing the separator of my invention.

FIG. 2 shows in cross sectional form a portion of my improved separator taken along the plane of section line 22 of FIG. 3.

FIG. 3 is a plan view, partly in section, showing the separator of FIG. 2 as seen from the plane of section line 3-3 of FIG. 2.

FIG. 4 is a cross sectional view taken along the plane of section line 4-4 of FIG. 3.

PARTICULAR DESCRIPTION OF THE INVENTION FIG. 1 shows at 10 a rotary compressor comprising matching, rotating gear elements which effect displacement of gas from inlet line 12 to outlet line 14. Line 12 receives low pressure Freon gas from evaporator 16, and line 14 receives compressed Freon gas and atomized oil. The oil is distributed to the rotary compressor through oil line 18, which is connected to the outlet side of an oil cooler 20. This oil cooler may be located adjacent the condenser 23 which forms a part of the refrigeration circuit. Portions of the cooling coil for the condenser 23 may be isolated from the refrigeration circuit and used instead as an oil cooling circuit. This will eliminate the need for providing a separate oil cooler 20. In any case, the oil distributed to oil line 18 is cooled by air passing over cooling coils through which the oil is caused to flow.

The discharge line leading from the compressor extends to the separator of my invention, which is indicated in schematic form in FIG. 1 by reference character 22. The Freon gas which is purged of oil is transferred through passage 24 to the inlet side of condenser 23. The outlet side of the condenser 23 communicates with the evaporator 16 through passage 24.

In a preferred embodiment of my invention, approximately 1 to 1.5 gallons per minute of oil is passed from the separator to the inlet side of the oil cooler through passage 26. A filler 28 may be located in this passage if this is desired.

The low pressure gas passing to the compressor through line 12 may be approximately 65 F. When it is compressed and mixed with oil, its temperature is raised to 200 F. and its pressure is raised to approximately 200 psi at 500 rpm. A slight temperature drop occurs as the oil is separated and returned through line 26 to the inlet side of the oil cooler. The temperature of the oil on the outlet side of the oil cooler may be approximately The condenser inlet temperature is approximately 5 less than the outlet temperature of the compressor. The

outlet temperature for the condenser is about 60 less than its inlet temperature. The condensate passes under pressure through flow restricting orifice 30 located in line 24 thereby reducing the pressure and allowing the liquid to evaporate in evaporator 16.

Unlike reciprocating piston compressors which have only about 1 percent to 4 percent of oil in the refrigerant, a relatively large proportion of oil is used in a vaporized form in the circuit illustrated in FIG. 1. A larger quantity of oil is required in the circuit because of the rotary compressor which has a need for a larger quantity of oil to effect sealing. The oil itself is preferably a synthetic lubricant of low solubility for the refrigerant. Because of the larger quantity of oil required for any given volume of refrigerant, the problem of separation becomes more important. This separating action is made possible by the improvement of my invention.

My improved separator includes a housing 32 which may be formed in two parts shown at 34 and 36. Each part'forms a portion of a cylinder. They are arranged in an overlapping relationship to permit a welded joint An inlet nozzle 40 communicates with the high pressure gas and oil line 14, a suitable fitting 42 being provided for this purpose. The discharge end of the nozzle is flattened, as shown in FIG. 4 at 44, and the angle to the nozzle is arranged in general tangential disposition with respect to the internal cylindrical wall 46 of the housing part 34.

A cylindrical baffle 48 is secured in sequential disposition within the housing part'34 and is welded at 50 to end wall 52 of the housing part 34. The end wall 52 is formed with-an opening 54 which communicates with a cylindrical screen 56. The screen is formed of 100 mesh wire. A coil spring 58 is arranged within the screen 56 to prevent collapsing. An end plug 60 is secured in the lower end of the screen 56. A cylindrical fitting on end plate 62 is positioned within the opening 54 and within the surrounding end of the screen 56. End plate 62 is formed with an opening to receive a fluid fitting 64 which-forms a part of the line 24 described previously.

The cylindrical chamber defined by the housing part 34 and the cylindrical, concentric baffle 56 functions as a swirl chamber for the gas and oil mixture that is discharged into it in a tangential direction from the nozzle 40. The centrifuging action thus produced causes the oil to separate and to pass downwardly under the force of gravity into a collecting chamber defined by the lower housing portion 36. A second screen 66 is situated at the base of the housing portion 36 so that it'may serve as a coalescer for the swirling fluid. The liquified oil separated from the admixture is collected and distributed through opening 68 formed in the base of housing portion 36. This opening forms a part of line 26 described previously.

In a preferred form of my invention approximately 48 ounces of liquid Freon and about 24 ounces of oil is used in the closed circuit. The length of the baffle 48 is slightly larger than the corresponding axial dimension of the screen 56. The baffle length is approximately one-third of the total length of the housing 32. In any case, the length is chosen so that it will at all times remain completely above the liquid level that might occur in the housing 32.

Having thus described a preferred embodiment of my invention, what i claim and desire to secure by US. Letters patent is:

l. A liquid gas separator for use in a refrigerating system employing a refrigerant and a lubricant of low solubility for the refrigerant, said separator being in communication with the discharge side of a compressor and the inlet side of the condenser, said separator comprising a cylindrical housing defining an upper swirl chamber portion and a lower liquid collector chamber portion, said cylindrical housing having an end wall portion extending across the top of said upper swirl chamber portion, said end wall portion having a centrally disposed opening coaxial with said cylindrical housing, a refrigerant outflow passage communicating with the upper swirl chamber portion, a lubricant flow exit passage communicating with the lower region of said housing, an entrance nozzle communicating with said upper swirl chamber portion of said cylindrical housing, said nozzle being in communication with the discharge side of said compressor and adapted to introduce an admixture of lubricant and refrigerant into said swirl chamber, the flow direction of the admixture through said nozzle being generally tangential with respect to the internal cylindrical surface of said swirl chamber, and a coalescer in the form of a pervious member arranged in general coaxial disposition with respect to said housing within said swirl chamber, said coalescer having a central collector region in communication with said refrigerant outflow passage, the lubricant introduced into said swirl chamber being centrifuged and drained under the force of gravity into said collector chamber and hence to said lubricant flow exit passage, said swirl chamber being defined in part by a cylindrical baffle concentrically disposed within said housing and surrounding said coalescer, said end wall portion having a central part which abuts said cylindrical baffle to which said cylindrical baffle is attached the axial length of said baffle and said coalescer being foreshortened a predetermined amount to avoid submerging of said coalescer in liquid collected in said collector chamber, said coalescer comprising a cylindrical wire mesh having multiple layers, a cylindrical fitting secured to the housing in said opening in said end wall portion and located within the upper end of said multiple layers of cylindrical wire mesh, said cylindrical fitting having an outflow opening coaxial with said cylindrical housing, said outflow opening receiving said refrigerant outflow passage, an end plug secured in the lower end of said multiple layers of cylindrical wire mesh, a spring situated in said wire mesh between said cylindrical fitting and said plug to prevent collapse of said wire mesh due to the pressure existing in said separator and a second coalescer screen situated in said lower liquid collector chamber portion and extending across the base of said collector chamber portion, liquified lubricant received in said lower liquid collector chamber portion being allowed to pass through said second coalescer screen prior to entering into said lubricant flow exit passage. 

1. A liquid gas separator for use in a refrigerating system employing a refrigerant and a lubricant of low solubility for the refrigerant, said separator being in communication with the discharge side of a compressor and the inlet side of the condenser, said separator comprising a cylindrical housing defining an upper swirl chamber portion and a lower liquid collector chamber portion, said cylindrical housing having an end wall portion extending across the top of saiD upper swirl chamber portion, said end wall portion having a centrally disposed opening coaxial with said cylindrical housing, a refrigerant outflow passage communicating with the upper swirl chamber portion, a lubricant flow exit passage communicating with the lower region of said housing, an entrance nozzle communicating with said upper swirl chamber portion of said cylindrical housing, said nozzle being in communication with the discharge side of said compressor and adapted to introduce an admixture of lubricant and refrigerant into said swirl chamber, the flow direction of the admixture through said nozzle being generally tangential with respect to the internal cylindrical surface of said swirl chamber, and a coalescer in the form of a pervious member arranged in general coaxial disposition with respect to said housing within said swirl chamber, said coalescer having a central collector region in communication with said refrigerant outflow passage, the lubricant introduced into said swirl chamber being centrifuged and drained under the force of gravity into said collector chamber and hence to said lubricant flow exit passage, said swirl chamber being defined in part by a cylindrical baffle concentrically disposed within said housing and surrounding said coalescer, said end wall portion having a central part which abuts said cylindrical baffle to which said cylindrical baffle is attached the axial length of said baffle and said coalescer being foreshortened a predetermined amount to avoid submerging of said coalescer in liquid collected in said collector chamber, said coalescer comprising a cylindrical wire mesh having multiple layers, a cylindrical fitting secured to the housing in said opening in said end wall portion and located within the upper end of said multiple layers of cylindrical wire mesh, said cylindrical fitting having an outflow opening coaxial with said cylindrical housing, said outflow opening receiving said refrigerant outflow passage, an end plug secured in the lower end of said multiple layers of cylindrical wire mesh, a spring situated in said wire mesh between said cylindrical fitting and said plug to prevent collapse of said wire mesh due to the pressure existing in said separator and a second coalescer screen situated in said lower liquid collector chamber portion and extending across the base of said collector chamber portion, liquified lubricant received in said lower liquid collector chamber portion being allowed to pass through said second coalescer screen prior to entering into said lubricant flow exit passage. 